Electrically variable impedance circuit
US4288707A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 8, 1979 |
| Grant date | Sep 8, 1981 |
| Priority date | — |
| Expiry date | Mar 8, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G1/0035
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An electrically variable impedance circuit in which a voltage-current converter circuit is provided to produce a current having a magnitude corresponding to an instantaneous input signal potential applied to an input terminal and a current variation of the voltage-current converter circuit is fed back to the input terminal, the current variation being controlled by a control signal to vary the circuit impedance seen from the input terminal. In order to expand the range of linearity in impedance, the voltage-current converter is so arranged that the varying component of its output current is linearly proportional to the instantaneous input signal potential, and a current converter circuit is provided which linearly converts the output current of the voltage-current converter circuit and whose output is coupled to the input terminal. The current converter circuit is comprised of a PN junction which develops a voltage which is the logarithm of the output current of the voltage-current converter and a transistor between the base and emitter of which is applied the voltage developed by the PN junction to produce a current which is the exponential of the voltage developed by the PN junct…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.